The patent was drafted very generally, but seems to focus on the volume (rather than elasticity) of the internal components. OTOH, it would be great if it were

The patent was drafted very generally, but seems to focus on the volume (rather than elasticity) of the internal components. OTOH, it would be great if it were even more generally drafted, since its priority date is in 1995. 1995+17 = 2012, so the world is now wide open for innovation in this area, unimpeded by patents (IANAL).